The overall efficiency of internal combustion engines, as they are currently used in motor vehicles, is typically maximal at those operating points which are close to full load and at low to moderate engine speeds. In partial-load operation, the energy contained in the fuel is not optimally utilized. As a result, the fuel consumption is higher than would be necessary per se. However, such partial-load operation is the normal operation in motor vehicles having high-performance internal combustion engines.
One may attempt to keep the operating point in the range of optimum efficiency as continuously as possible via an optimum design of manual shift transmissions and shifting strategies in automatic transmissions, for example, having a continuous transmission ratio. Another possibility is the concept of so-called “half-engine operation” in which one part of the cylinders operates at a comparatively high load and thus at a comparatively good efficiency. The other cylinders are shut off by interrupting the injection of fuel into these cylinders. For example, in an eight-cylinder internal combustion engine, four cylinders are shut off in this way.
An object of the present invention is to provide a method which allows low-emission operation of an internal combustion engine as much as possible while simultaneously allowing low fuel consumption.